Art of generating steam



A, c, wQop 1,830,155 ART o1;l GENERATgLNG S'TEM Filed Nov. y26, 1926 5Sheets-Sheet Y1 Nov. 3, 1931.

NOV. 3, 1931. A` Q WOOD 1,830,155

ART OF GENERATING STEAM Filed Nov. 26, 1926 5 Shee'cs--Sheec` 2 INVENTORA TTORNE Y Nov. 3, 1931. A. c. woon ART OF GENERAIJNG STEAM Filed Nov.'26,. 1926 5 Sheets-Sheet 3 INVENToR /bek C Wood ATTORNEY F'ileQNov. 26,1926 5 Sheets-Sheet 4 INVENTR /be/" C VUOd ATTORNEY Nov. 3, 1931. A. c.WOOD 1,830,155

ART 0F GENERATING STEAM Filed Nov. 26 5 Sheets-Sheet 5 o oooooo By QCbArm/wv Patented Nov. 3, 1931 PATENT OFFICE ALBERT C. WOOD, 0FPHILADELPHIA, PENNSYLVANIA 'ART or GENERATING STEAM Application ledNovember 26, 1926. Serial No. 150,665.

My invention is an improved steam` genera tor adapted primarily for theutilization of fuels which are combustible in suspension and produceintense heat insuring quick and'efficient generation of steam from waterwhich comprised in primary generating elements located substantiallysymmetrically on op; posite sides of the longitudinal center line ofthe'apparatus, and the end walls ofthe furnace are completely orpartially protected by screens or curtains of circulating tubes formingsecondary generating elements coni stituting integralpart of ,the boilerand so connected therewith through headers as to induce natural andrapid circulation upward of wate rlhe primary generating elements areflanked by vertical dues containing heat absorptive economizing devicesseparated from the primary generating nests by flue walls which areprotected against deteriora tion by the heat absorption of such tubenests and economizing devices. Y

A streamof heated air and fuel combustible in suspension is injectedpreferably through the upper part of the furnace into the combustionchamber between the banks of generating tubes and heated gases areevolved from such stream byA combustion. The combustible stream isdischarged downwardly with considerablevelocity but near the bottom ofthe combustion chamber the fuel stream with the gases evolvedtherefromdivides or spreads and flows reversely upward around thecentral descending stream or column and along the primary and secondarygenerating -H tubes; the upflowing flamevolumeor heated gasesencompassing or flanking and maintaining the ignition of the centraldownflowing fuel stream by radiant heat and intimate contact andeffecting rapid vaporization of the fluid in the generating elements.The reversal of the course of the gases adjacent to the bottom of thecombustion chamber pro motes the deposition of ash therefrom in discreteparticles and avoids or minimizes the fusion lof the ash on heatabsorptive generating surfaces. Y

rlfhe downward flow of the central stream or column and the upward flowof the outer stream or columns are accelerated by the relative weightofthe several columns since the central column is relatively much colderand heavier than the intensely hot and largely expanded outer column.Additional supplies of heated air may be admitted under control at thebottom of the combustion chamber to 4intensifythe furnace action andaccelerate t-he upward flow. The ignition of the descending column offuel and air by the heat from the ascending' flaming gases on eitherside of the furnace obviates the necessity for anyconsiderable areas of'refractory lining for the maintenance of combustion.

The hearth or bottom wall of the setting is .preferably protected fromthe effects of the heat of thev products of combustion not only by theadmission of auxiliary air adjacent thereto and the upward diversion ofthe burning gases but also by the provision of oppositely inclined setsof circulating tubes communicating with drums or headers at the bases ofthe primary generating elements. Definite and rapid circulationthroughthese tubes results from the fact that the lower portions of thetubes are further from the fire, are shielded partially .by the upperportions of the oppositely 1nclined tubes, and the lower portions of thetubes are exposed to and cooled by the auxiliary air admitted tothelower part of the furnace; consequently these tubes not only affordprotection to the hearth but generate steam and equalize the water levelbetween the boiler elements on the opposite side of vthe furnace.

of settings and refractory linings are greatly reduced, spaceeconomized, efliciency increar-ed and maintenance costs reduced by myimproved assembly and relationship of the several elements and themovements of the fuel, air, products of combustion, vater and steaminduced thereby.

T he characteristic features and advantages of my improvements will morefully appear' from the following description and the accompanyindrawings of illustrative and preferred embodiments thereof.

ln the drawings, F l is a vertical sectional view taken on the line 1-1of Fig. l of a steam generator embodying my improvements, a portion ofthe structure cut away by the section being projected by dot and dashlines; lEig. :2 is a vertical sectional view of the same generatortal-:en on the lme 2--2 '-l of F ig. el; Fig. 3 is a horizontalsectional view taken on the line 3-3 of Figs. 1 and 2; Fig. l is a topplan view of the generator shown in the preceding figures; Fig. 5 is avertical sectional view of a modified embodiment of my invention; Fig.t5 is a vertical sectional view of a further modification of myinvention, while Fig. T a vertical sectional view taken on the line 'i 7of Fig. this ligure being a sectional development on median line (3 6 ofFig. 7, the part to the left of this line in Fig. 7 being omitted fromthis figure, since it is substantially symmetrical with that shown.

As illustrated in Figs. 1 to l inclusive of the drawings, the primarygenerating elements are arranged substantially symmetrically ou oppositesides of a combustion chamber 1 in the boiler setting 2; each primary igelement comprising an upper drum 3, ai lower drum el, a bank of uprightupflovv' tubes 5 and abanl; of upright downiiow tubes 6. The primarygenerating elements have connected vith opposite ends of the drumsthereof wall protecting elements comprising headers T connecting thedrums 3, headers 8 connecting the drums Ll, and screens or curtains oftubes 9 connecting the respective pairs of headers i' and 8 to shield orcurtain the end walls 10 of the furnace. T he headers 7 preferablycommunicate with the drums below the normal water level thereof andbehind the shields 11, and the steam spaces of the drums l are prefe1ably connected by a. row of insulated equalizer tubes i2 ljing abovethe refractory top wall or roofof the furnace. 'lie radiation from thisrefractory roof aids combustion.

The drums el are connected by rows of oppositely inclined tubes 13 and14 which cross one another above the approximate center of the hearth orbottom wall 15, which protected by the heat absorptive capacity of thetubes. The upper or outlet ends of the tribes 13 and 14 are connected tothe respective drums t adjacent to the plane of connecti on therewith ofthe headers 8 and extend radially from the drums to points beyond theirline of intersection. The tubes are there bent in a curve so that theirlower or inlet ends make radial connections with the drums below thelevel of the outlets from the complementary row of tubes and the headersDefinite and rapid circulation through the tubes 13 and 14 is assuredsince the lower portions of the tubes are farther from the fire than theupper portions of the tubes, the lower portions of each row of tubes ispartially shielded by the upper portions of the other row of tubes, andthe lower portions of the tubes are directly exposed to the coolingeffect of air supplied through ports 16 below the respect-ive drums.

later is supplied to the respective drums 3 through valve controlledtubes 17 from economizers 18 located in substantially vertical fines 19at the sides of the combustion chamber. The gases from the combustionchamber enter the flues 19 through the openings 20 and pass through theflu-es on their way to the stack or other draft producing means. Theflues may also have therein air preheater tubes :21 or superheater tubesor both, and may be controlled by dampers The steam collecting drums 3may be connected through tubes 23 with superheaters which are shownpositioned between the tube banks 5 and G of the primary generating`elements, but which, may be elsewhere lo"- cated, as for instance in thelower part of the fines 19. The superheaters communicate through thetubes Q5 with the common superheated steam outlet 26.

Fuel combustible in suspension, such as powdered coal, sawdust, liquid,or gas is introduced into the combustion chamber through the top 2T ofthe furnace substantially midway between the primary generating elements5 and 6. i

As illustrated, pulverized fuel is fed from a hopper 28 supported abovethe furnace to a fuel supply pipe 29 by power driven screw conveyors 30.The tube 29 contains air portsI 31 for the admission of air foradmixture with the fuel in its passage through the supply pipe which ispartly housed within a heated air supply conduit 3:2, which togetherwith the fuel supply pipe discharges to the top of the combustionchamber through an opening 33 in the roof of the furnace. y rl`heconduit 32 is supplied with heated air, under control of a damper 84,from a main 35 coinmunicating with the air preheaters Q1 to which air issupplied under pressure by a blower 36 through the conduit 37. Theheated air main 35 also supplies preheated air through damper controlledbranches of a conduit 38 to the air ports 16 beneath the drums l.

The upright tribes 5 have fixed thereto baffles comprising plates 40 anddeflectors l1 inlll) clined downwardly toward the upright tubes v6,which are preferably provided with battle plates42 to cooperate with theplates 4() and delectors 41 in concentrating the heated gases on thetubes 6: The battles 40, 41 extend upwar ly from the drums 4 to pointsbelow the level of the drums 3 and the bailles 42 extend downward fromthe" drums Sto points above the level of the drums 4. The substantiallyvertical or upright disposition of the main tube nests and battlesreduces to a minimum the accumulation thereon of dust and dirt and theadhesion theretoV of fused particles of ash. y

Iii operation, fuel and heated air are discharged downvi'ardly undersome pressure and with considerable velocityv into the combastionchamber where the relatively cool column of combustible matter isignited primarily by the radiant heat and llame of the intensely hot andlargely expanded ascending columns rising around the downtlowing column.The downward flow of the central column and the upward flow of the outercolumn is accelerated by the differences in their relative weights. Thedescending column upon its ignition and expansion divides and flowsupwardly along the tubes 5 and 9, the combustion being intensified andthe iow accelerated by the admission of heated air under pressurethrough the ports 16. The products of combustion rising alongthe tubes 5sweep over the tops of the baflles 40 and over the superheaters 24 andaredeflected downwardly over the tubes 6, from which they pass to theflues 19 where further heat is absorbed by the economizing devices 18and 2l before discharge to thestack.

By my improvements there is provided a compact structurerin which theradiant Aheat losses and the ille'ffects of air infiltration are reducedto a minimum and the cost of settings, and refractory7 linings are verygreatly reduced. The generator is operable eficiently at high workingtemperatures without serions deterioration, since the side walls 19 arebanked and shielded on one side by the primary boiler elements 5, 6, andon the other side by the secondary elements 18 and 'Z1 designed toabsorb heat from gases of lower temperature: the end walls are protectedby the curtain or screen formed by the tubes 9 so connected to inducenatural and rapid circulation upwardly therethrough; the hearth. isprotected by the intersecting tubes 13 and 14 and the admission of airthrough the openings 16, andthe refractory roof is protected by thecooling eit'ect of the admission ofthe fuel and air and the diversionlaterally of the upflowing n heated gases at the sides. Y

Fig. 5 illustrates an adaptation or modification of the generator shownin the previous tig-ares and which while generally similar thereto isdesigned primarily for the utilization of fuels whichv requireconcentrated iiitense heatfor ignition and for the absorp-v tion ofgreater portions of the heat from the 'products of combustion'v beforedischarge thereof to the fines than would be absorbed inv a generator ofthe type illustrated in-.Figs 1 to 4. VHence in this'modifiedconstruction while economizer devices may be placed in the flues, thegenerator may be efficiently operated without them.

In the modified construction, tubes 5 are slightly inclined and a largernumber of tubes 5 and 6 are used in each primary generating nest. VThelower ends of the tube banks of each nest. are connected toa drum 4 asbefore, but the upper ends of the respective banks 5 aie connected withthe respective drums 3a while the upper ends of the respective banksbare connected with the'i'espective drums 3?). Each drum 3a is connectedwith a drum 3b by tubes'45 and 4G 'to equalize pressures and provide forcircu lation between them; The drums 3a are conn'ected with oneanotherby the tubes 12 and b a sectional' to a header 8d havin@` lesdepending from the drums and connected by a median length substantiallybelow the level ofv the drums. The tubes 9 are'V connected Vto thebottom sectional header 8b and with the niediaii'portion of` the uppersectional header 8a soas toV leave above said last named header exposedend wall sections 47 of refractory material, which become highlyheatedand facilitate ignition of the fuel supplied'through the roof ofthefurnace. They deflectors at the tops of the baffles 40 are inclinedupwardlytoward the tubes lVhen boilers are constructed of considerablewidth, shown in this gure, 'it is sometimes desirable to support thetubes` 13 and 14 intermediate their lengths by a partition or wall 48,which also aids in separating and deflecting upwardly the air currentsadmitted through inlets such as 16, or through air inlets at the ends ofthe furnace.

Figs. 6 and 7 illustrate a further adaptation or modification of thegenerator shown in the previous figures, which, while generall-y similarthereto, is intended for effecting 1 combustion of the fuel bydischarging it,

with a suitable initial air supply, upwardly within the combustionchamber, and intermediate the primary generating elements on eitherside,in such a way, and by such means, that the burning gases evolvedfrom the fuel are caused to divide beneath the roof of the combustionchamber and to owdownwardly y on either side of the upwardly ascendingfuel and air column, the radiant heat and flame m of the intensely hotdowntlowing columns assistingand. acceleratingthe ignition of theupflowing column.V In this form of my iii- `ventioii, the secondary airsupply for c0mpleting combustion is preferably admittedat the top ofthecombustion chamber, the

so admitted serving to cool the roof of the combustion chamber and toreverse the flow of the gases thereunder.

In the modified construction shown in Figs. G and 7, the tube banks 5and G, constituting the primary generating elements, are connected todrums 3 and 4, as in Fig. 1. The tube banks on either side of thecombustion chamber 1 are, however, in the modified form, preferablyinclined toward each other so that the distance between drums 8 is lessthan the distance between drums 4. The end walls are water cooled, inthe upper portions at least, by water circulating tubes 9, connectingbetween headers 7a and 8a, in turn connecting, respectively, with drums3 and 4 on either side of the combustion chamber 1. Hearth protectingtubes 14a and 146 connect the drums 4 with the drum 4a, located belowand midway between the drums 4. Tubes 12 connect the steam spaces ofdrums 3, one with the other. An air tight roof, 12a, encloses the tubes12, below, which is the combustion chamber roof 2, preferablyconstructed with refractory blocks suspended from beams 2a. An opening2b is provided in the combustion chamber roof for admitting secondary orsupplementary air for completing combustion. Baiiles 40 on the outermostrows of tubes extend downwardly from drums 3 to points above the levelof drums 4. Ballies 41, extending between adjacent rows of tubes in tubebanks 5 and 6, serve to direct the` products of combustion into activeContact with tubes 6, and to prevent short circuiting of the gases inthe space between adjacent rows of tubes of the tube banks 5 and (i.Battles 40 and 41 are preferably supported by lugs 41a, welded toadjacent tubes 5 and G. respectively. Bullies 42 on the outermost rowsof tubes 6, extend from drums 4, upwardly to a point below the level ofdrums 3, and are preferably secured to and held in place by U-boltspassing around the tubes and through the battle 42, or by lugs 42awelded to these tubes. Super-heaters 24, connected by pipes 23 with thetops of drums 8, may be installed in the triangular space between thebattles 42, the walls 19 and the roofs 19. The products of combustion,after passing downwardly over the superheaters 24, escape through theopenings 2O into the flue 19, under control by the dampers 22.

Pulverized fuel is fed from a hopper 28, supported above the furnaceinto tubes 29; at either end of the boiler, by power driven screws 30',right and left hand on either side of media-n line 6-6 of Fig. 7. Thetubes 29 contain air ports 31 for the admission of heated air from theair supply conduits 82', which are in turn supplied by the air supplyconduits 35'; connecting` with air preheaters in tine 19. Thesepreheaters 19 are however not shown in detail in Fig. 6, since they aresimilar in character, arrangement and location to the air preheaters 21in Fig. 1. The air conduits 82', and the fuel tube 29 within it, bendinwardly and upwardly at their lower extremities, and pass through theend walls 10 in such a way as to discharge the fuel, with an initial airsupply, upwardly into the combustion chamber, in opposing streams,which, impinging the one against the other, are broken up andintermingled in such a way as to greatly aid the ignition and combustionprocess, and to cause the resultant stream of gases, after ignition, toflow in an upright course toward the roof of the combustion chamber,where, meeting with a seeondary preheated air supply delivered throughdamper controlled conduits 38, and discharged through openings 2?) inthe combustion chamber roof, a further admiXture of air takes place.,and the burning gases are deflected downwardly in streams on eitherside, along and in partial contact with the tubes 5 of the primarygenerating elements, and pass under the ends of battles 40 and 41',thence upi yardly in contact with tubes G over the top of baflles 42',into the triangular spa ccs occupied by the superheaters 24, and thencedownwardly between walls 19 and baliies 42', to and through openings 20,into tlues 19, and thence upwardly, past dampers 22. to the stack orother draft producing means.

it will be apparent to those skilled in the art, that fuel and airdischarged from socalled unit pulverizers, can be utilized with myinvention in lieu of the fuel and air supplied by the means herein shownand diescribed.

Having described my invention, I claim.

l. A steam generator comprising ay coinbustion chamber having banks oftubes on the opposite sides thereof, drums adjacent to the lower part ofsaid combustion chamber on opposite sides thereof and connected withsaid banks of tubes, and oppositely inclined tubes connecting the drumsaforesaid.

2. A steam generator comprising a combustion chamber, drums on oppositesides of said combustion chamber adjacent to the bottom thereof,`generating elements projectiim upwardly from the respective drums, a setot tubes ha\f'ing outlets to one of said drums and inlets from the otherof said drums, a set of tubes having` outlets to said last named drumabove the inlets to said lirst named tubes and inlets from the other ofsaid drums below the outlets of the first named tubes and means forsupplying fuel to said combustion chamber. Y

3. A steam generator comprising a combustion chamber havingr a hearth,means for discharging products of combustion from the upper portion ofsaid chamber toward said hearth, drums on opposite sides of said chamberadjacent to said hearth, oppositely inclined tubes crossing one anotherand con lill) necting said drums, parts of tubes aforesaid partiallyshielding parts of other tubes aforesaid and said hearth from the actionof said products of combustion, means for flowing air over saidpartially shielded parts of said tubes, and upright generating elementseX- tending upwardly from said drums on opposite sides of saidcombustion chamber.v

4. A steam generator comprising a combustion chamber surrounded by heatabsorptive water circulating elements and a wall preventing lateralingress of air to said chamber, means Jfor discharging a stream of fueland heated air under pressure downward in said combustion Chamber7 andmeans for discharging a. stream of heated air under pressure into thebottom. of said combustion chamber to deflect said descending streamupwardly against said circulating elements.

In witness whereof I have hereunto set my name this 24th day of Nov.1926.

ALBERT C. WOOD.

